She said: “This is an elimination process, and that’s how I’m dealing with it. It’s one of the most important things to happen in 21 years.

“I never imagined this would happen so soon after the Daily Mirror ­investigation on Kos this summer.”

Kerry, of Sheffield, added: “I really feel South ­Yorkshire Police are determined to help me find out exactly what has happened to Ben.

"This has been a 21-year nightmare you don’t wake up from.”

The team of 10 search experts drafted in from police forces across the UK will today be joined by six others in a bid to solve one of the longest running missing persons inquiries in history.

Mum: Kerry Needham yesterday waiting on news (Image: Roger Allen)

They are being led by South Yorkshire’s Detective Superintendent Matt Fenwick, who is investigating our revelations that 21-month-old Ben may have been ­accidentally buried under the rubble by a JCB driver working outside the home.

Kerry will wait anxiously at a secret ­location for news as the dig, expected to last up to 10 days, starts tomorrow.

Mr Fenwick said yesterday: “One of the lines of inquiry is that we want to clear the ground from where Ben originally went missing, to if you like, finalise that as a line of inquiry.

“I’m taking over some search experts with expertise in looking at ground work, to establish the possibility that some remains could be there.

“From the Greek authority perspective they’re also providing a level of expertise and they will be working very closely with us and providing a large number of staff who can assist in the search.

“There are multiple lines of inquiry at the moment that are certainly possibilities as to what’s happened to Ben, but this is just one line of inquiry that, by the work that we propose, should finalise that, to the best we can.”

The developments on Kos follow our investigation in May that revealed where little Ben may have been buried.

We also told how the mound was formed with tons of earth being dumped by JCB digger driver Konstantinos Barkas and other builders in an ­overgrown field next to the house.

Missing: Ben in a smiling portrait (Image: Phil Spencer)

And only a handful of police searched for the missing tot by torchlight because at least three hours elapsed before his disappearance was reported.

The unprecedented move follows a landmark diplomatic ­operation between Greece and Britain.

And the dig is unique because British officers have been allowed to seal off part of a foreign country and treat it as a crime scene. At the request of Athens’ most senior police chiefs, Home Office experts will use sonar and 3D equipment to scan the ground for bones.

Cadaver dogs trained to search out human remains will also form part of the hunt.

A forensic anthropologist and archaeologist from a UK university are involved in the operation.

A sample of Ben’s DNA, from the heel blood test done at birth, was obtained by British police in a High Court ruling last year. That could be crucial if remains are found.

The Mirror saw the first British officers arriving in Kos on a flight from Manchester.

Search: The Needhams property (white house) with the mound of earth to the right (Image: Roger Allen)

Blond, blue-eyed Ben vanished on July 24, 1991 while his grandparents Eddie and Christine Needham were looking after him along with Kerry’s younger brothers Stephen and Daniel.

Kerry, then 19, was out working as a waitress at a hotel in Kos where the family had intended to settle.

Residents in the coastal village of Psalidi, where the hillside track to the home starts, have been kept in the dark about the police operation.

But shopkeeper Xanthippi Agrelli, 59, once accused by the Needhams of being involved in Ben’s ­disappearance, said she was sure the answer to the mystery rests on Kos.

She volunteered as the family’s translator in the first desperate days of the search for the youngster.

Last night she broke down in tears at the scene and said: “It has been so awful for all of these years to live with this hanging over us

“I have never been able to understand why they don’t look around this house. They were digging here.

"Next door there was a new building. In the field next door it was full of high wild grass.

“They were filling it with stones and earth. Ben was a tiny boy and like all tiny boys he would have been curious about the noise from the big trucks.

"As soon as we heard about Ben we all said the same thing… the poor little baby was the victim of a horrible accident.”

Dig site: Mirror's Tom Parry next to mound of earth next to where Ben disappeared (Image: Roger Allen)

In May, the Mirror tracked down digger driver Mr Barkas who confirmed he was excavating earth for a property to be built 50 yards from the house where the Needhams were staying.

Speaking for the first time, the 61-year-old told us: “Yes, I was the man with the JCB that day. Loads of earth were being taken to clear the ground for the new house.

“I think people were misled in thinking the child was abducted. Could there have been an accident? I don’t think so but no one really knows what happened.

“The little boy was two years old and the thorns in that field were as high as my waist.”

Mr Barkas also revealed he has given a ­statement to police.

Other theories about Ben’s disappearance include one that he may have been murdered and buried at the site.

Mirror investigation: How we broke the story on the burial theory (Image: Daily Mirror)

Another is that he may have been accidentally killed then dumped in a shallow grave by the culprit who knew it would later be further covered by tons of earth.

Greek detectives are convinced the most likely explanation is that Ben, who would be 23 this year, died on the day he vanished.

A source said: “This idea is a lot more plausible than him being abducted.

“Going back 21 years, there were only two or three families up there. There would be no reason for anyone else to go up there.

“A stranger would have needed to be watching the house beforehand, and then would have snatched him in broad daylight before secreting him off the island by boat or plane.

“What cops do know for sure is that the dumper truck was driving up and down the track next to the house.

"This carried on in the days and weeks after Ben had been reported missing.”

New revelation: Our investigation led to police looking at case again

But Mr Fenwick also shares mum Kerry’s hope that her son is alive.

He added: “I have two children, two girls, what wouldn’t I do to find my girls? Kerry is like that, what won’t she do?

“What hasn’t she done to find her boy? And Kerry won’t give up. She will carry on until she knows what has happened to Ben.

“It would be just fantastic wouldn’t it, if I got a phone call. We do get sightings and we do follow lines of inquiry.

“I can’t describe how that would be for me, never mind for Kerry.”

Kerry believes Ben was snatched by someone driving a white car along the lane at the time.

The vehicle sighting was reported to Kos police by the four builders working on the new house, who included Mr Barkas.

Hunter: The device which will be used

Forensic scientists will search for Ben using the same equipment that located the buried victims of killers Fred and Rose West.

Ground penetrating radar was initially developed to detect land mines but is used to help police in searches where sniffer dogs or metal detectors have failed.

Electromagnetic waves are sent into the ground, which bounce back if they hit anything unusual.